Cables, ropes, and other elongate bodies are often used to tow or lift objects. For example, military helicopters or ships may extend a cable with a sensor attached to an end of the cable into a body of water and tow the sensor in the water for collecting data, such as the location of enemy vessels or mines. Stops, such as tow stops, cable stops or carriage stops, are often used to help prevent an extended cable or rope used to tow a sensor from being extended further out of the helicopter, ship or other vehicle. Of course, other devices use similar stops to prevent a cable or rope from further extending when an object is being towed or held by the rope or cable.
Cable stops, tow stops and carriage stops can include a bulged portion of a cable. One example of such a stop is disclosed in U.S. Pat. No. 3,577,605 to Fischer et al. Cables having such stops may be extended from a device or vehicle to tow a sensor or other object. To stop the extension of the cable, a cable catch, such as, for example, the cable catch disclosed in U.S. Pat. No. 4,768,820 to Barone, or tow ball is often used to directly engage the bulged portion of the cable (i.e. the cable stop) to prevent the cable from extending further out of the device or vehicle. The engagement of this bulged portion with the cable catch or tow ball stops the cable from further extension and permits a vehicle or device attached to the cable to tow the extended cable or hold the extended cable. By engaging the cable stop, the axial load of the cable is transferred to the cable catch or tow ball.
Such cable stops, tow stops or carriage stops typically experience relatively high compressive forces on the stops and transfer relatively high splitting forces to the cable catch or tow ball used to hold them. The tension may be caused from resistance that results from various activities. For example, tension is created when the cable holds an object and is extended into a body of water, towed behind a ship or vehicle, or retracted back to the vehicle.
Cable catches and tow balls are often designed to incur very large loads of force because cable catches or tow balls generally incur both the transferred axial loads and splitting forces when holding the cable stop, tow stop or carriage stop. The cable catches or tow balls required to hold or retain such stops are usually complex structures that are extremely heavy so that the cable catch or tow ball can effectively hold the cable stop. Such cable catches and tow balls are normally very expensive to produce and maintain.
Cable stops, tow stops and carriage stops often unravel or split due to the high compressive forces and relative motion between the stop and the cable catch or tow ball used to hold them. The compressive forces and relative motion cause local wear and can initially break down the stop. Cable movement, particularly twisting, can also cause breakdown of the cable stop, tow stop, or carriage stop and usually causes the stop to unravel or split.
A device is needed that prevents a cable stop, tow stop or carriage stop from breaking down as a result of interacting with cable catches or two balls and does not cause the cable catches or tow balls to be loaded with high splitting forces. Preferably, the device is sized and configured so it can retain cable stops, carriage stops and tow stops and be held by low weight tow balls or cable catches that are less expensive to produce or maintain than the heavy tow balls or cable catches typically required to engage and retain the stops.